On 9 May 2012, at 10:30 AM, Michael_google gmail_Gersten wrote:

My Mac Pro has a pair of quad-core CPUs, but both iStat Menus and MenuMeters 
show a bar chart with 16 bars rather than the expected 8 bars.  Is this a Lion 
thing?  There were only 8 bars under Snow Leopard.  Why does Lion seem to think 
I have 16 cores?

You have 8 physical cores, but each core can do two things; it can
pretend to be 16 cores, 8 physical and 8 logical.

My MacBook Pro will attempt to only use the physical cores normally,
turning on the logical ones only in very high usage, so I'm guessing
that they are not as fast as real cores.

On 9 May 2012, at 10:29 AM, Bruce Carter wrote:

I believe that is due to HyperThreading.

Hi Michael and Bruce,

Thanks for the information.  Is this new in Lion?  I'm sure I only saw 8 cores 
displayed in Snow Leopard (and earlier).

Does Lion actually provide a benefit from HyperThreading (and logical cores), 
or is performance the same and only displayed differently?

Thanks,

Gregg

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